Reflections 07/24/97
Robert Kern Curtis

Parallax

The Earth is at the center of the universe and everything revolves around the Earth. This is the position which won the day in ancient Greece. The heliocentric model of Aristarchus was rejected, and both Plato who understood the phases of the Moon as the result of the Moon's revolving about the Earth and reflecting the Sun's light, and Aristotle were in the forefront of the advocates of geocentricity! The source of light and heat should have been at the center, but the significant scientific objection to this position is the observed absence of parallax.

If the Earth were not still, they reasoned, there would be some apparent motion of the stars due to the motion of the Earth! Even Aristarchus, the founder of trigonometry, could measure no parallax for any star. Finally Ptolemy's highly predictive mathematical work based on the geocentric model doomed Aristarchus's sun centered notions. Even Galileo was unable to measure any parallax in the heavens; it was not until 1838 that the parallax of any star was measured.

Even though the religious inclinations of the ancients favored having Apollo at the center of things, they were unable to overcome the strong scientific evidence against such a notion: the fact that no parallax could be observed!





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